Get rid of Alternative instance for Parser

Author: evancz

compiler/src/Parse/Expression.hs

@@ -6,8 +6,6 @@ module Parse.Expression
   where
 
 
-import Control.Monad (guard)
-
 import qualified AST.Source as Src
 import qualified Elm.Name as N
 import Parse.Primitives
@@ -300,34 +298,36 @@ exprHelp start (State ops expr args end pos) =
           spos <- W.whitespace
           hint (E.AfterOpExpr opName) (checkSpace spos)
           newStart <- getPosition
-          hint (E.AfterOpExpr opName) $ oneOf $
-            [ -- negative terms
-              do  guard ("-" == opName && end /= opStart && opEnd == newStart)
-                  rawTerm <- term
+          hint (E.AfterOpExpr opName) $
+            if "-" == opName && end /= opStart && opEnd == newStart
+            then
+              -- negative terms
+              do  rawTerm <- term
                   newEnd <- getPosition
                   newPos <- W.whitespace
                   let arg = A.at opStart newEnd (Src.Negate rawTerm)
                   exprHelp start (State ops expr (arg:args) newEnd newPos)
-
-            , -- term
-              do  newExpr <- possiblyNegativeTerm newStart
-                  newEnd <- getPosition
-                  newPos <- W.whitespace
-                  let newOps = (toCall expr args, op) : ops
-                  exprHelp start (State newOps newExpr [] newEnd newPos)
-
-            , -- final term
-              do  (newLast, newEnd, newPos) <-
-                    oneOf
-                      [ let_ newStart
-                      , case_ newStart
-                      , if_ newStart
-                      , function newStart
-                      ]
-                  let newOps = (toCall expr args, op) : ops
-                  let finalExpr = A.at start newEnd (Src.Binops (reverse newOps) newLast)
-                  return ( finalExpr, newEnd, newPos )
-            ]
+            else
+              oneOf
+                [ -- term
+                  do  newExpr <- possiblyNegativeTerm newStart
+                      newEnd <- getPosition
+                      newPos <- W.whitespace
+                      let newOps = (toCall expr args, op) : ops
+                      exprHelp start (State newOps newExpr [] newEnd newPos)
+
+                , -- final term
+                  do  (newLast, newEnd, newPos) <-
+                        oneOf
+                          [ let_ newStart
+                          , case_ newStart
+                          , if_ newStart
+                          , function newStart
+                          ]
+                      let newOps = (toCall expr args, op) : ops
+                      let finalExpr = A.at start newEnd (Src.Binops (reverse newOps) newLast)
+                      return ( finalExpr, newEnd, newPos )
+                ]
 
     , -- done
       let finalExpr = toCall expr args in

compiler/src/Parse/Primitives/Internals.hs

@@ -12,7 +12,7 @@ module Parse.Primitives.Internals
 
 
 import Prelude hiding (length)
-import qualified Control.Applicative as Applicative ( Applicative(..), Alternative(..) )
+import qualified Control.Applicative as Applicative (Applicative(..))
 import Control.Monad
 import qualified Data.ByteString.Internal as B
 import Foreign.ForeignPtr (ForeignPtr, withForeignPtr)
@@ -158,14 +158,6 @@ instance Applicative.Applicative Parser where
     (<*>) = ap
 
 
-instance Applicative.Alternative Parser where
-    {-# INLINE empty #-}
-    empty = allTheOptionsFailed
-
-    {-# INLINE (<|>) #-}
-    (<|>) = oneOfHelp
-
-
 oneOf :: [Parser a] -> Parser a
 oneOf parsers =
   foldr oneOfHelp allTheOptionsFailed parsers